For connecting an electrical wire and a terminal in a wire harness for motor vehicles, crimp joining, in which an electrical wire caulked and crimped by a terminal called open-barrel type, has been commonly known. However, in such a wire harness, if moisture or the like adheres to the connecting part of the electrical wire and the terminal, oxidization of the surface of the metal used for the electrical wire progresses, increasing the resistance at the joint part. Also, if different metals are used for the electrical wire and the terminal, corrosion between different metals may progress. The progress of corrosion of metal materials at the connecting part causes cracks or contact failure at the connecting part, and its effect on product life is unavoidable. Particularly in recent years, a wire harness having electrical wires made of aluminum alley and terminals made of copper alloy has been in practical use, the problem of corrosion at the joint part has became noteworthy.
Here, if moisture adheres to the contacting part of different metals such as aluminum and copper for example, so-called electrolytic corrosion may occur due to difference in corrosion potential. Since the potential difference between aluminum and copper is especially large, corrosion on the side of aluminum, which is an electrically base metal, progresses. Thus, the connection state between a conductive wire and a crimp terminal becomes unstable, causing an increase in contact resistance or in electrical resistance due to decrease in wire diameters, and, furthermore, disconnection of the wire, which may result in malfunction or breakdown of the electrical components.
For such a wire harness having different metals contacting with each other, a method using a terminal having a tubular crimping portion of which one end is closed has been proposed, for example (Patent Document 1): the method includes inserting an end part of an electrical wire into the tubular crimping portion, and then crimping the tubular crimping portion by caulking so as to prevent the end part of the core wires from adhesion of moisture such as rain water or sea water.